Some sensors in the induction system or exhaust system of an internal combustion engine must be monitored or adapted from time to time, and this must be carried out under the condition that the induction system and/or exhaust system is flooded with fresh air and thereby contains a defined amount of oxygen. In addition, some actuators in the induction system or exhaust system, for example injectors for the injection of small amounts of fuel into the induction system or exhaust system, require monitoring and adapting for the purpose of compensation under such defined conditions.
Defined conditions under which sensors or actuators in the induction system or exhaust system can be monitored or adapted are in particular achieved if the drive train is opened by disengaging the clutch, wherein engine braking is terminated by interrupting the fuel delivery, so that fresh air flows through the internal combustion engine while the revolution rate thereof decreases freely under the influence of friction and inertia.
The length of the period of time with a freely falling revolution rate that can be used for monitoring or adapting is however relatively short and may not be sufficient to fully flood the induction system and/or exhaust system with fresh air and still carry out the monitoring or adaptation tasks thereafter. Moreover, the length of the useful period of time depends on the revolution rate of the engine at the point in time of the opening of the drive train, and the rate of decrease in the revolution rate depends on the inertia of the engine and the friction of the engine.
Longer useful periods of time for monitoring and adaptation tasks are achieved if the monitoring or adapting are carried out in an engine braking mode with the drive train closed, but the useful length of such periods of time or the rate of decrease in the revolution rate depend on the current driving conditions and also on the drive train being kept closed for long enough, so that here too no well-defined conditions for monitoring and adaptation tasks are achieved.
As an example, the period of time available for monitoring and adaptation tasks may be extended to a required duration by reducing free rolling with the clutch disengaged for a duration, but this may be desirable for the driver.
The object of the invention is to specify a method for monitoring or adapting sensors or actuators in the induction system or exhaust system of an internal combustion engine that provides a defined and sufficiently long period of time for this purpose without irritating the driver.
In one example, the issues described above may be addressed by a vehicle method, comprising: monitoring and adapting a plurality of sensors and actuators in each of an induction system and an exhaust system of an internal combustion engine during a period of time in which fresh air is flowing through the internal combustion engine without fuel delivery, wherein the period of time in which fresh air is flowing through the internal combustion engine without fuel delivery is extended by transferring a positive torque produced by an electric motor to the internal combustion engine, the positive torque exerted by the electric motor on the internal combustion engine being smaller than a negative torque resulting from an internal friction of the internal combustion engine.
In this way, by transmitting a torque produced by electric motor to the internal combustion engine, the rate of decrease of engine speed over time (rpm/second) may be reduced and the period of time (window) in which fresh air flows through the internal combustion engine with the fuel delivery cut off and in which monitoring or adapting is carried out may be extended by.
DE 10 2007 026 354 A1 and EP 1 807 278 B1 disclose hybrid electric vehicles with an internal combustion engine that can be held at a defined revolution rate by means of torque produced by electric motor when fuel delivery is turned off if it runs with freely decreasing revolution rate or in the engine braking mode when fuel delivery is turned off. This enables the resumption of fuel delivery to be inhibited when the revolution rate falls below a minimum revolution rate in order to save fuel, such as for a completely different purpose than with the present disclosure.
The method according to the disclosure is particularly suitable for being carried out in a motor vehicle with a hybrid drive by means of an internal combustion engine and at least an electric motor, such as an electric motor that can propel the vehicle or can at least support the internal combustion engine when propelling the vehicle. Such an electric motor is also capable of driving the internal combustion engine at the revolution rates required for carrying out the method.
It is also possible that the method could be carried out in a micro hybrid vehicle, if for example the micro hybrid vehicle comprises a crankshaft starter motor that can also be used as a generator that can produce positive torque at higher revolution rates than are required for starting the internal combustion engine.
During the monitoring or adapting, the at least one electric motor may exert a positive (i.e. driving) torque on the internal combustion engine that is smaller than the negative (i.e. braking) torque resulting from the internal friction of the internal combustion engine. The drive train of the motor vehicle may be open during the monitoring or adapting, but the method may also be used to extend an engine braking mode with the drive train closed if monitoring or adapting is currently taking place and the revolution rate of the engine is decreasing too rapidly under the current driving conditions.
The positive torque that is produced by electric motor, which is exerted on the internal combustion engine during the monitoring or adapting, may be essentially constant. In this way, well-defined conditions are obtained for the monitoring or adapting. The exertion of the positive torque is preferably ended once the monitoring or adapting is completed.
The disclosure can not only be used to monitor or adapt sensors or actuators, but also to monitor or adapt positions of components of the internal combustion engine, such as for example for the adaptation of tooth angle and top dead center.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.